Institute of Molecular Biology and Biophysics SD RAMS, Novosibirsk, Russia.
Cancer Med. 2013 Oct;2(5):654-61. doi: 10.1002/cam4.108. Epub 2013 Aug 5.
Heparansulfate proteoglycans (HSPG) play an important role in cell-cell and cell-matrix interactions and signaling, and one of the key enzymes in heparansulfate biosynthesis is d-glucuronyl C5-epimerase (GLCE). A tumor suppressor function has been demonstrated for GLCE in breast and lung carcinogenesis; however, no data are available as to the expression and regulation of the gene in prostate cancer. In this study, decreased GLCE expression was observed in 10% of benign prostate hyperplasia (BPH) tissues and 53% of prostate tumors, and increased GLCE mRNA levels were detected in 49% of BPH tissues and 21% of tumors. Statistical analysis showed a positive correlation between increased GLCE expression and Gleason score, TNM staging, and prostate-specific antigen (PSA) level in the prostate tumors (Pearson correlation coefficients GLCE/Gleason = 0.56, P < 0.05; GLCE/TNM = 0.62, P < 0.05; and GLCE/PSA = 0.88, P < 0.01), suggesting GLCE as a candidate molecular marker for advanced prostate cancer. Immunohistochemical analysis revealed an intratumoral heterogeneity of GLCE protein levels both in BPH and prostate cancer cells, resulting in a mixed population of GLCE-expressing and nonexpressing epithelial cells in vivo. A model experiment on normal (PNT2) and prostate cancer (LNCaP, PC3, DU145) cell lines in vitro showed a 1.5- to 2.5-fold difference in GLCE expression levels between the cancer cell lines and an overall decrease in GLCE expression in cancer cells. Methyl-specific polymerase chain reaction (PCR), bisulfite sequencing, and deoxy-azacytidin (aza-dC) treatment identified differential GLCE promoter methylation (LNCaP 70-72%, PC3 32-35%, DU145, and PNT2 no methylation), which seems to contribute to heterogeneous GLCE expression in prostate tumors. The obtained results reveal the complex deregulation of GLCE expression in prostatic diseases compared with normal prostate tissue and suggest that GLCE may be used as a potential model to study the functional role of intratumor cell heterogeneity in prostate cancer progression.
硫酸乙酰肝素蛋白聚糖（HSPG）在细胞-细胞和细胞-基质相互作用和信号转导中发挥重要作用，其中糖醛酸 C5-差向异构酶（GLCE）是硫酸乙酰肝素生物合成的关键酶之一。GLCE 在乳腺癌和肺癌发生中表现出肿瘤抑制功能；然而，目前尚无关于前列腺癌中该基因表达和调控的资料。在这项研究中，在 10%的良性前列腺增生（BPH）组织和 53%的前列腺肿瘤中观察到 GLCE 表达降低，在 49%BPH 组织和 21%的肿瘤中检测到 GLCE mRNA 水平增加。统计学分析显示，在前列腺肿瘤中，GLCE 表达增加与 Gleason 评分、TNM 分期和前列腺特异性抗原（PSA）水平呈正相关（Pearson 相关系数 GLCE/Gleason=0.56，P<0.05；GLCE/TNM=0.62，P<0.05；和 GLCE/PSA=0.88，P<0.01），提示 GLCE 可能是晚期前列腺癌的候选分子标志物。免疫组织化学分析显示，在 BPH 和前列腺癌细胞中 GLCE 蛋白水平存在肿瘤内异质性，导致体内 GLCE 表达和不表达的上皮细胞混合存在。体外对正常（PNT2）和前列腺癌细胞系（LNCaP、PC3、DU145）进行的模型实验显示，癌细胞系之间 GLCE 表达水平存在 1.5-2.5 倍差异，癌细胞中 GLCE 表达总体下降。甲基特异性聚合酶链反应（PCR）、亚硫酸氢盐测序和脱氧氮杂胞嘧啶（aza-dC）处理鉴定了 GLCE 启动子的差异甲基化（LNCaP 为 70-72%，PC3 为 32-35%，DU145 和 PNT2 无甲基化），这似乎导致了前列腺肿瘤中 GLCE 表达的异质性。研究结果揭示了与正常前列腺组织相比，前列腺疾病中 GLCE 表达的复杂失调，并表明 GLCE 可能被用作研究前列腺癌进展中肿瘤内细胞异质性的潜在模型。
